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    SubjectRe: [Xen-devel] [PATCH 0/5] Xen PV on HVM fixes
    On Wed, 1 Dec 2010, Jeremy Fitzhardinge wrote:
    > On 12/01/2010 10:22 AM, Stefano Stabellini wrote:
    > > Hi all,
    > > this patch series is a collection of fixes for Xen PV on HVM.
    > >
    > > The first two patches fix two pirq remapping problems with MSIs, they
    > > have been sent to the list few times already for comments.
    > > The three following patches are new and fix save/restore bugs.
    > Are you targeting these at 3.6.37-rc?

    Yes, because the bugs are pretty serious.

    > If so, each changelog commit
    > should explicitly say what bug is being fixed, and what the impact of
    > the bug is. The last 3 are OK, but it isn't clear to me whether the
    > first two are strictly bugfixes or not.

    The first patch fixes find_unbound_pirq that otherwise would be based on
    PHYSDEVOP_get_nr_pirqs that is actually not supported by Xen,
    therefore it would fail. So find_unbound_pirq would return a number
    starting from nr_irqs that might very well be out of range in Xen.

    The symptom of this bug is that when you passthrough an MSI capable pci
    device to a PV on HVM guest, Linux would fail to enable MSIs on the

    The second patch fixes a bug in xen_hvm_setup_msi_irqs that manifests
    itself when trying to enable the same MSI for the second time: qemu is
    responsible for remapping MSIs into pirqs and considers the old MSI to
    pirq mapping still valid at this point but xen_hvm_setup_msi_irqs
    would try to assign a new pirq anyway.

    A simple way to reproduce this bug is to assign an MSI capable network
    card to a PV on HVM guest, if the user brings down the corresponding
    ethernet interface and up again, Linux would fail to enable MSIs on the

    I have updated the first two commit messages with these info, the branch
    is still the same:

    git:// 2.6.37-rc4-pvhvm-fixes

     \ /
      Last update: 2010-12-02 15:45    [W:0.020 / U:6.940 seconds]
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